1. Field of the Invention
This invention relates generally to swimming pools and personal safety systems, and more particularly, to a system for a child or adult anti-drowning system comprising a radio transmitter system worn by a person, and a radio receiver system, located next to a swimming pool, that responds or reacts if the person wearing the radio transmitter system approaches the swimming pool area.
2. Description of the Related Art
Historically, anti-drowning safety devices for children or adults have fallen into two main categories: The first category is the type of safety device that involves actual contact with the water by a device worn by a person. Upon contact with the water, the device signals a receiver, utilizing some portion of the electromagnetic spectrum, and the receiving device then broadcasts some type of alarm. The second category of safety devices involves those in which actual water contact does not occur. In this category, the person to be protected is wearing a transmitter that establishes a radio link, in a continuous mode, with a receiver. This type of system generally involves a loop antenna surrounding the swimming pool. The receiver receives a continuous signal from the loop antenna's reception of the person's transmission signal. When the person approaches within a certain distance of the loop antenna, the receiver detects an increased signal strength from the loop antenna. This increased signal strength results in an alarm condition as described in the first category.
These systems possess drawbacks, however. The water contact category systems require actual contact with the water before an alarm occurs. This means that the person to be protected is already in the water and may be drowning even as the alarm is activated. Obviously, this system responds much too late. The non-water contact systems also have drawbacks, however. These systems establish a continuous radio link between the transmitter worn by the person and the receiver located poolside. This continuous radio link then varies in signal strength depending on the proximity of the person and their transmitter to the swimming pool receiver and the loop antenna. The drawbacks to the continuous radio link systems include: interference may cause a signal interruption thus resulting in false alarms, or no alarms whatsoever; and the person may stray outside the reception area thereby resulting in false alarms, system failure, etc; and finally, the transmitter required to be worn by the person is quite large and is strapped onto the person as a backpack which results in a cumbersome and easily damaged system. Additionally, this system is not liked by children beyond the initial thrill of the first five minutes of wearing it, as the system will get in the way during the child's regular activities such as sitting in a chair, trying to lie down, etc.
Therefore a need existed for a system that would activate before a person was actually in the water. Additionally, a need existed for a system that did not require a continuous radio link between the transmitter worn by the person and the receiver located poolside. Yet another need existed for a system that would not be subject to interference or loss of the radio link. A final need existed for a system that would be small, compact, and durable, such that the wearing of the system by the person would be easily accomplished and would not interfere with a person's normal activities.